• Title/Summary/Keyword: Pitch gain

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An Effect of Pitch Gain-Scheduling on Shaft Vibration Response of Wind Turbine (풍력터빈 축 진동 응답에 대한 피치 게인-스케쥴링의 효과)

  • Lim, Chae-Wook;Jo, Jun-Chul
    • The KSFM Journal of Fluid Machinery
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    • v.15 no.2
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    • pp.36-40
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    • 2012
  • Pitch control of wind turbine is activated above rated wind speed for the purpose of rated power regulation. When we design pitch controller, its gain-scheduling is essential due to nonlinear characteristics of aerodynamic torque. In this study, 2-mass model including a vibration mode of drive-train for a 2 MW wind turbine is considered and pitch control with gain-scheduling using a linearization analysis of the nonlinear aerodynamic torque is applied. Some simulation results for the pitch gain-scheduling under step wind speed are presented and investigated. It is shown that gain-scheduling in pitch control is important especially in the region of high wind speeds when there exists a vibration mode of drive-train.

An Investigation on Step Responses of Pitch PI Controller for a 2MW Wind Turbine Using Bladed S/W (Bladed S/W를 이용한 2MW급 풍력터빈에 대한 피치 PI 제어기의 계단응답 고찰)

  • Lim, Chae Wook
    • The KSFM Journal of Fluid Machinery
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    • v.18 no.1
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    • pp.59-64
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    • 2015
  • The pitch control system in wind turbines becomes more and more important as the wind turbines are larger in multi-MW size. PI controller has been applied in most pitch controllers and it has been known that gain-scheduling is essential for pitch control of wind turbines. A demo model of 2 MW wind turbine which represents the whole dynamics of wind turbine including dynamic behaviors of blade, tower and rotational shaft is given in the commercial Bladed S/W for real wind turbines. In this paper, some results on step responses of the pitch PI controller and effectiveness of gain-scheduled pitch PI controller are presented through the Bladed S/W for the 2 MW wind turbine.

Adaptive Control of Spacecraft with Elastic Appendages (유연한 부속물을 가진 우주선의 적응제어)

  • Lee, Ho-Jin;Lee, Keum-Won
    • Journal of the Institute of Convergence Signal Processing
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    • v.9 no.2
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    • pp.159-163
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    • 2008
  • In this paper, a simplified type of adaptive controller using Nussbaum gain for the control of the spacecrapt with elastic appendages is suggested. This method doesn't need the information of the high frequency components in transfer function. While the pitch angle tracks the desired value by this method, the elastic modes are also stabilized. Only pitch angle and the pitch rate are used for the design of the output feedback controller. Especially all system parameters and the high frequency gain are assumed to be unknown. For design simplicity, a controller is designed by using only the linear part, and it's shown to satisfy the nonlinear system by the simulation with basic explanations. By using the Lyapunov function, the stability of the suggested algorithm is demonstrated, and also the effectiveness of the suggested algorithm is verified by showing the computer simulation results.

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The Phoneme Synthesis of Korean CV Mono-Syllables (한국어 CV단음절의 음소합성)

  • 안점영;김명기
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.11 no.2
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    • pp.93-100
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    • 1986
  • We analyzed Korean CV mono-syllables consisted of concatenation of consonants/k, t, p, g/, their fortis and rough sound and vowels/a, e, o, u, I/by the PARCOR technique, and then we synthesized those speech by means of the phoneme synthesis controlling the analyzed data. In the speech analysis, the duration of consonants decreases in the rough sound, the lenis and the fortis in turns. And also the gain of them decreases in the same tendency. The pitch period increases more and more in vowels following the rough sound, the fortis and the lenis in turns. We synthesized the lenis and the fortis by controlling the duration and the gain of the rough sound, and vowels following the fortis and the rough sound by controlling the pitch period and the duration of vowels following the lenis. As the results, the synthesized speech quality is good and we make certain it is possible to make a rule to the phonome synthesis in Korea speech.

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Light Output Characteristics of Rounded Prism Films in the Backlight Unit for Liquid Crystal Display

  • Lee, Won-Gyu;Jeong, Jin-Ha;Lee, Ji-Young;Nahm, Kie-Bong;Ko, Jae-Hyeon
    • Journal of Information Display
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    • v.7 no.4
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    • pp.1-4
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    • 2006
  • The optical performances of rounded prism films were investigated using a ray tracing technique. The angular distribution of the luminous intensity was obtained as functions of the prism pitch and the curvature of rounded apex and valley of prism arrays. The gain of the on-axis luminance decreased with decreasing curvature (increasing diameter) and pitch. The existence of the curved area on the prism film decreased the recycling efficiency of the prism film, i.e., the rays which would otherwise have been recycled through total internal reflections via the prism surfaces were refracted on the curved regions and redirected toward directions other than the on-axis direction. Quantitative correlation between the luminance gain and the curvature in addition to the prism pitch was obtained, which might serve as basic data for the optimization of prism films and the manufacturing processes.

A study on the gain-scheduling of missile autopilot (유도탄 제어기의 이득-스케듈링에 관한 연구)

  • 송찬호;김윤식
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10a
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    • pp.355-360
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    • 1991
  • A method of autopilot gain-scheduling is presented for missiles which have heavy aerodynamic coupling between pitch and yaw channels due to high maneuverability. Pitch and yaw, autopilot are cross-coupled, and their feedback gains are scheduled by total acceleration and bank angle for given Mach number and height. Bank angle information is obtained by using a simple estimator. By computer simulation, it is shown that the proposed method is superior to other existing methods.

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Numerical Analysis on Heat Gain of Liquid from Ambient Air with Various Fin Heights and Pitches of Fin-and-Tube Heat Exchanger in Hybrid Solar Collector (핀-튜브 열교환 구조를 갖는 복합집열기에서 핀 높이 및 간격에 따른 공기열 이용 액체 가열 성능에 관한 수치해석 연구)

  • Choi, Hwi-Ung;Fatkhur, Rokhman;Lyu, Nam-Jin;Yoon, Jung-In;Son, Chang-Hyo;Choi, Kwang-Hwan
    • Journal of the Korean Solar Energy Society
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    • v.36 no.3
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    • pp.53-61
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    • 2016
  • Solar assisted heat pump system uses solar thermal energy as a heat source of evaporator of heat pump. So, COP can be enhanced as well as collector efficiency. For improving performance of this system, some research about hybrid solar collector that has fin-and-tube heat exchanger has been conducted. This collector can get a thermal energy from ambient air for liquid heating, so heated liquid can be used as a heat source of evaporator in heat pump even the solar radiation is not enough. In this study, numerical analysis was conducted for confirming heat gain of liquid according to fin height and pitch of fin-and-tube heat exchanger in collector. As a result, higher heat gain was obtained on lower fin height and narrow fin pitch, but the pressure drop also increased with increment of heat gain. Thus the JF factor considering both heat transfer enhancement and pressure drop was investigated and the maximum value was shown when the fin height and pitch were 40mm and 45mm. So it is considered that this installation condition has a highest heat transfer improvement when comparing with pressure drop. However heat gain of liquid at this condition was less than the other installation conditions of fin pitch on same height. Then, after establishing a proper minimum heat gain of liquid, actual production and experiment of collector will be conducted with fin height and pitch showing maximum JF factor and satisfying selected minimum heat gain of liquid on the basis of results of this study.

Packet Loss Concealment Algorithm Using Pitch Harmonic Motion Estimation and Adaptive Signal Scale Estimation (피치 하모닉 움직임 예측과 적응적 신호 크기 예측을 이용한 패킷 손실 은닉 알고리즘)

  • Kim, Tae-Ha;Lee, In-Sung
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.14 no.4
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    • pp.247-256
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    • 2021
  • In this paper, we propose a packet loss concealment (PLC) algorithm using pitch harmonic motion prediction and adaptive signal amplitude prediction and. The spectral motion prediction method divides the spectral motion of the previous usable frame into predetermined sub-bands to predict and restore the motion of the lost signal. In the proposed algorithm, the speech signal is classified into voiced and unvoiced sounds. In the case of voiced sounds, it is further divided into pitch harmonics using the pitch frequency to predict and restore the pitch harmonic motion of the lost frame, and for the unvoiced sound, the lost frame is restored using the spectral motion prediction method. When the continuous loss of speech frames occurs, a method of adjusting the gain using the least mean square (LMS) predictor is proposed. The performance of the proposed algorithm was evaluated through the objective evaluation method, PESQ (Perceptual Evaluation of Speech Quality) and was showed MOS 0.1 improvement over the conventional method.

Design of Individual Pitch Control and Fatigue Analysis of Wind Turbine (풍력발전시스템 개별피치제어설계 및 피로해석에 관한 연구)

  • Jeon, Gyeong Eon;No, Tae Soo;Kim, Guk Sun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.1
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    • pp.1-9
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    • 2014
  • Structural loading on a wind turbine is due to cyclic loads acting on the blades under turbulence and periodic wind field. The structural loading generates fatigue damage and fatigue failure of the wind turbine. The individual pitch control(IPC) is an efficient control method for reducing structural loading. In this paper, we present an IPC design method using Decentralized LQR(DLQR) and Disturbance accommodating control(DAC). DLQR is used for regulating rotor speed and DAC is used for canceling out disturbances. The performance of the proposed IPC is compared with CPC, which was designed with a gain-scheduled PI controller. We confirm the effect of fatigue load reduction with the use of damage equivalent load(DEL).

Oxidative Stabilization Behaviors of Petroleum-based Isotropic Pitch Fiber Spun by Melt-blown Method

  • Kim, Chan;Lee, Su-Hyun;Kim, Young-Min;Yang, Kap-Seung
    • Carbon letters
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    • v.2 no.3_4
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    • pp.170-175
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    • 2001
  • A petroleum-based isotropic pitch fiber spun by melt-blown method was oxidized in air flow at various conditions. The oxidized pitch fiber obtained was tested for its infusibility and its elemental composition during the process of stabilization. The structural changes were traced by using solvent solubility, FT-IR spectroscopy, and elemental analysis. The samples showed a gradual increase in weight with increasing the oxidization temperature. The weight gain of sample oxidized at $320^{\circ}C$ for 10 min was about 4.5%. The concentration of the pyridine and toluene soluble fraction decreased with an increase in stabilization temperatures. The oxygen uptaken in the stabilization process converted aliphatic side chains into the carbonyl groups. As stabilization proceeded, the more ether and carboxylic acid groups were formed through the oxidations of aldehyde and primary alcohol, and then the carboxylic acid was dehydrated to be aromatic anhydride.

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